Managing Smoke Risk from Wildland Fires: Northern California as a Case Study

Karina Chung, Tianjia Liu, Makoto Kelp, Karn Vohra, Dana Skelly, Matthew Carroll, Joel Schwartz, Loretta Mickley

Smoke fine particulate matter (PM2.5) from increasing wildfires in the western United States threatens public health. While land managers often prioritize reducing wildfire risk in the wildland-urban interface, the impact on regional air quality from mitigating wildfire spread is less explored. We develop a framework to quantify wildfire contributions to smoke exposure and assess targeted land management strategies. This data-driven approach integrates fire emissions and smoke transport to generate a smoke risk index at 0.25°×0.25° resolution. We deploy the smoke risk index in an online tool, enabling stakeholders to analyze smoke risk under various scenarios of burned area, fuel consumption, and land management. Using Northern California as a case study, we estimate that in 2020, targeted land management in the 15 highest-risk areas (~3.5% of the total) could have reduced smoke exposure by 17.6%. However, most prescribed burns conducted from 2017-2020 did not overlap with these high-risk zones. Our framework also estimates excess deaths from smoke PM2.5 exposure, attributing ~36,400 (95% CI: 25,400-47,200) deaths nationally due to western US fires in the year following the 2020 fire season. Our adaptable tool can incorporate higher-resolution datasets and help stakeholders prioritize fuel treatment and fire suppression to mitigate smoke exposure risks.